Display Driving Circuit With TFT Voltage Compensation Feedback
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Solution Overview
Problem
Existing driving circuits for display panels, such as LED, OLED, mini LED, and micro LED panels, suffer from variations in transistor characteristics due to manufacturing processes like LTPS and a-Si, leading to output voltage errors and non-ideal bias influences from parasitic capacitive coupling, affecting the gate voltage of thin-film transistors.
Innovation Solution
A special circuit design incorporating compensation transistors within the driving circuit to compensate for voltage fluctuations in driving transistors, using structures like 2T1C, 7T2C, or 8T2C configurations with capacitors to stabilize the gate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin-film transistors are used in the driving circuit, then the circuit can be manufactured using LTPS, a-Si or oxide TFT processes, but variation in transistor characteristics causes voltage errors and non-ideal bias influence
Solution Approach 1:
The patent implements a feedback mechanism where the compensation transistor continuously monitors and adjusts for voltage errors caused by transistor characteristic variations. The compensation transistor's gate is connected to the driving transistor's gate, and its source is connected to the driving transistor's source through a capacitor, creating a feedback loop that automatically compensates for voltage deviations without requiring external intervention.
Solution Approach 2:
The patent changes the electrical parameters of the compensation transistor to match and counterbalance the variations in the driving transistor. By configuring the compensation transistor with similar characteristics and connecting it in parallel with the driving transistor, the system dynamically adjusts the compensation transistor's operating parameters to offset voltage errors, thereby maintaining stable output voltage despite process variations.
2Adaptability or versatility
If more thin-film transistors are included in the driving circuit, then the circuit functionality is enhanced, but parasitic capacitive coupling causes non-ideal bias influence on voltage levels
Solution Approach 1:
The compensation transistor acts as an intermediary element that mediates the parasitic capacitive coupling effects. By introducing this additional transistor configured in parallel with the driving transistor, the system creates a compensatory path that counteracts the non-ideal bias influences from parasitic capacitances, thereby stabilizing voltage levels while maintaining enhanced circuit functionality.
3Reliability
If a compensation transistor is added to the driving circuit, then voltage errors are compensated and reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the driving circuit into functionally distinct components: the driving transistor for primary current control and the compensation transistor for voltage error correction. This segmentation allows each transistor to be optimized for its specific function while working together in a coordinated manner, improving overall voltage accuracy without creating excessive complexity.
Solution Approach 2:
The compensation transistor is merged with the driving transistor in a parallel configuration, sharing common connections to the light emitting unit and power supply. This merging approach allows the compensation function to be integrated into the existing circuit structure with minimal additional components, achieving voltage error compensation while keeping the overall device complexity manageable.
Data Source
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AI summary
A driving circuit for driving a light emitting unit is provided. The driving circuit includes a driving transistor, a switch transistor, an emitting transistor, a first capacitor and a first compensation transistor. The switch transistor is coupled to the driving transistor. The emitting transistor is coupled between the light emitting unit and the driving transistor. The first capacitor is coupled to the driving transistor. The first compensation transistor is coupled to the first capacitor. A first end of the first compensation transistor and a first end of the emitting transistor receive same signal.